Rotary motor with fluid pressure biased vane

ABSTRACT

A vane-type air motor including a cylinder, opposite end walls and an eccentric rotor rotating within the cylinder and carrying radially moving vanes sliding in slots. Pockets are provided in the end walls for accumulating and storing substantial volumes of air under pressure to urge the vanes outwardly against the cylinder as they are traveling in portions of the cylinder between the high and low pressure portions of the motor chamber. Such pockets are separate from the high and low pressure portions of the motor chamber and are arranged to avoid interconnecting such pressure portions to prevent forming direct leakage paths between said pressure portions.

United States Patent Kramer et al.

[451 Feb. 11,1975

[ ROTARY MOTOR WITH FLUID PRESSURE 3/1966 Bent 418/82 3,434,655 3/l969Bellmer 418/80 [75] Inventors: Leo Kramer, Skillman,ll l..l.; HaroldPrimary Examiner john J. vrablik Athens Attorney, Agent, or Firm-WalterC. Vliet [73] Assignee: lngersoll-Rand Company, New

York, NY. [57] ABSTRACT [22] Filed: June 1, 1973 A vane-type air motorincluding a cylinder, opposite end walls and an eccentric rotor rotatingwithin the [2]] App! cylinder and carrying radially moving vanes slidingin Related US. Application Data slots. Pockets are provided in the endwalls for accu- [63] Continuation of Ser- No. 178 623, Sept 8, 197]mulating and storing substantial volumes of air under abandon pressureto urge the vanes outwardly against the cylinder as they are travelingin portions of the cylinder be- [52] U.S. Cl. 418/82 tween the high andlow Pressure Portions of the motor 51 Int. Cl. F016 21/00, F03c 3/00Chamber, Such pockets are Separate from the g and [58] Field of Search418/79, 82, 267, 268 low Pressure Portions of the motor chamber and arearranged to avoid interconnecting such pressure por- [56] ReferencesCited tions to prevent forming direct leakage paths between UNITEDSTATES PATENTS Said Pressure 3,086,475 4/1963 Rosaen 418/268 5 Claims, 3Drawing Figures l6 LAP PORTION l2 1? I8 l l 20 l' 2| 2 1 a 22 9 k 23 i24 y PATENTEDFEBI 1 I915 3.865.520

l6 LAP PORTION TORS IN LEO KRAME HAROLD E HARRIS, JR.

BY '3 EM @W ATTORNEY 1 ROTARY MOTOR WITH FLUID PRESSURE BIASED VANE Thisis a continuation of application Ser. No. 178,623, filed Sept. 8, 1971,and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to improvements influid motors and more particularly to rotary motors having vanes slidingin a slotted rotor.

Heretofore, vane-type rotary fluid motors have had unsatisfactoryoperating characteristics at low speeds. While centrifugal forces urgethe vanes outwardly against the cylinder at high speeds, such forces areunavailable at low speeds and the radial positions of the vanes areunpredictable. In general, at low speeds when the vanes are not movedoutwardly against the cylinder with sufficient force, excessive leakageor blow-by" occurs across the vanes reducing the torque or power of themotor and generally causing erratic motor performance. Attempts to solvethis problem include the application of fluid pressure beneath the vanesby means of kidney-shaped ports located in the end walls of the motorchamber, but this has not been entirely successful. Such ports cannot beextended to continue to feed pressure beneath a vane while the vane istraveling in an area between the high and low pressure portions of thecylinder without resulting in excessive leakage between such pressureportions. As a result, at low speeds the vanes usually fail to remainextended outwardly against the cylinder to seal between the high and lowpressure portions of the motor chamber while moving between theseportions. It is also important for the vanes to be fully extended duringthe power stroke of the motor to avoid the loss of torque and power.

SUMMARY OF THE INVENTION The principal object of this invention is tosubstantially eliminate or minimize the foregoing problems in prior artfluid motors.

Another important object of the invention is to provide means forinsuring that the vanes of a vane motor are moved outwardly against itscylinder while traveling between high and low pressure portions of themotor chamber, to avoid excessive leakage or blow-by occurring acrossthe vanes and to improve the torque and power output of the motor.

In general, the foregoing objects of the invention are attained byproviding pockets or spaces in the end walls of a motor located betweenand spaced from the high and low pressure portions of the motor chamberand communicating with the vane slots as they travel between the highand low pressure portions. The pockets accumulate and retain asufficient volume of fluid under pressure to apply such pressure beneaththe vane as it travels past the pocket for maintaining the vane extendedduring such passage thereby insuring that the vane maintains a sealbetween the high and low pressure portions of the motor chamber toprevent excessive leakage or blow-by and to insure that the vane rideson the cylinder during its power stroke.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described inconnection with the accompanying drawings wherein;

FIG. 1 is an axial section of an air motor containing an embodiment ofthe invention and is taken on the line 1--1 in FIG. 2;

FIG. 2 is a cross section taken on the line 22 in FIG. 1; and

FIG. 3 is an axial section of a second embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT The air motor 1 shown in the drawingincludes a casing 2 formed by a cylinder 3 and a pair of end plates 4and 5 closing the ends of the cylinder 3. The end plates 4 and 5 areattached to the cylinder by suitable means such as bolts (not shown).

A cylindrical rotor 7 is mounted eccentrically within the cylinder 3 andcontains a pair of shaft ends 8 and 9 extending from opposite ends ofthe rotor through and rotatably mounted within bearings 10 supported onthe respective end plates 4 and 5. The rotor 7 includes a series ofangularly spaced radially extending slots 11, each housing a slidingvane 12 adapted to engage the interior periphery 14 of the cylinder 3.The ends 15 of the rotor 7 are flat and seat against the end plates 4and 5 with slight clearances therebetween allowing the rotor 7 to rotatefreely but substantially preventing fluid leakage across the rotor ends15.

The portion of the cylinder 3 that is located closest to the eccentricrotor 7 is known as the lap point and is designated the lap portion 16,being shown in FIG. 2 by a brace symbol. A pair of fluid passages 17 and18 are provided in the end plate 5 and terminate in respective fluidports 19 and 20 located on opposite sides of the lap portion 16. Theports 19 and 20 are connected to respective branch passages 21 and 22extending to respective kidney ports 23 and 24 for feeding pressure fromthe respective ports 19 and 20 to the vane slots 11 beneath the vanes 12for urging such vanes outwardly as they pass a respective port. Thepassages 17 and 18 are connected to a conventional valve system (notshown) whereby one of the passages 17 and 18 is connected to a highpressure air source and the other to atmosphere. The two ports 19 and 20generally define two spaced pressure portions designated 27 and 28extending around the rotor 7, as shown in FIG. 2. The portion of thecylinder 3 opposite the lap portion 16 and between the pressure portions27 and 28, where the vanes 12 are fully extended and where the powerstroke of the motor takes place, is shown by the brace 31. Theparticular connection of the passages 17 and 18 to the pressure sourceand to the atmosphere will determine the direction of rotation of themotor. For example, if the port 20 is connected to the air pressuresource, the rotor 7 will rotate in a clockwise direction as shown inFIG. 2.

Looking at FIG. 2, it will be recognized that the pressure in the kidneyports 23 and 24 may be effective to move each vane 12 outwardly as it ispassing a kidney port, but such pressure is not connected to the vaneslot 11 while the vane is moving between the two pressure portions 27and 28, for example, moving through the lap portion 16. If the vane 12does not remain engaged with the cylinder while passing between the twopressure portions 27 and 28, it will fail to provide a proper sealbetween the pressure portions and, as a result, excessive blow-by of theair will occur from the high pressure portion to the pressure portionconnected to atmosphere. In addition, if the vane 12 does not engage thecylinder during the power stroke of the motor, the torque and power ofthe motor is greatly reduced.

Although there is a small volume of air pressure in the bottom of theslot 11 and some air leaks into the bottom of the vane slot 11 while itis moving between the two pressure portions, such pressure isineffective to assure extension of the vanes 12 at slow speeds. Thepurpose of this invention is to solve this problem by insuring that thevanes remain engaged against the cylinder periphery 14 while they arepassing between the pressure portions 27 and 28, for example, across thelap portion 16 or across the other portion 31 of the cylinder.

This invention includes the provision of pockets 33 and 34 in the endplates 4 and located between the ends of each of the kidney ports 23 and24, closed by the rotor ends and spaced from such kidney ports, thuseliminating direct communication between the pockets and the kidneyports. The pockets 33 and 34 are essentially closed spaces or chambers.These pockets accumulate and trap substantial volumes of fluid underpressure flowing between the high and low pressure portions 27 and 28 ofthe motor chambers. Such trapped air volumes are effective to expand andurge' the vanes 12 outwardly against the cylinder 3 as they are passingthe pockets 33 and 34. We such found that the use of such pockets is anextremely effective answer to the very difficult problem of attaininggood low speed characteristics in vane-type air motors. The conventionalvane-type air motor is generally unpredictable and uncontrollable atspeeds below 100 RPM whereas our invention provides an air motor thatcan be operated at speeds down from 5 to 10 RPM without encounteringexcessive blow-by problems, loss of torque and power, and erraticoperating characteristics.

Designers of previous motors attempting to attain good low speedperformance have attempted to maintain a very small clearance at the lapportion 16, for example, in the range of 0.00] to 0.003 inches thatsometimes caused such motors to seize, particularly when operating underwide temperature conditions or dusty conditions. This inventioneliminates the need for such small lap portion clearances and we havefound that we can use clearances in the range of 0.015 to 0.02 incheswithout harming the performance of the motor.

EMBODIMENT OF FIG. 3

The embodiment of FIG. 3 shows the use of the novel pockets of thisinvention with a motor having a primary exhaust port 36 located midwaybetween the two pressure ports 19 and 20. In a motor of this type, thepressure ports 19 and 20 cover a much smaller arc of the motor sincepressure on the rotor vanes is essentially relieved by the primary port36 as the vanes cross the point where they are fully extended. In thisembodiment we locate a pocket 33 in the lap portion 16 of the motor anda pair of pockets 37 and 38 spaced from the kidney ports 23 and 24 andalso spaced on opposite sides of the primary exhaust port 36. Here againthe pockets do not extend into either the pressure portions 27 and 28 orthe area where the vane 12 crosses the primary exhaust port 36 in orderthat such pockets cannot serve as a passage for interconnecting the highand low pressure areas of the motor chamber. The pockets 37 and 38 serveto pop" the vanes 12 out against the cylinder during the power stroke ofthe motor.

While several embodiments of the invention are shown and described indetail, this invention is not limited simply to the specificallydescribed embodiments; but contemplates other embodiments and variationsutilizing the concepts and teachings of this invention.

We claim: 1. A sliding vane fluid motor comprising: a cylinder includingan opposed pair of spaced end walls;

rotor mounted to rotate in said cylinder between said end walls about anaxis eccentric to the axis of said cylinder and having a series of vaneslots extending longitudinally and outwardly toward the cylinder;

a vane sliding in each of said vane slots for engaging the cylinder asthe rotor rotates;

a pair of angularly spaced kidney ports in one of the cylinder end wallslocated in spaced angular relationship about the axis of the rotor andcommunicating with the ends of the vane slots as the rotor rotates tosupply fluid to and exhaust fluid from the vane slots; and

at least one closed pocket provided in each of said end walls in opposedrelationship and angularly located about the rotor axis between andspaced from both of said ports, said pocket being effective to trap avolume of fluid under pressure for urging the vanes outwardly as thevane slots travel past said pocket.

2. A sliding vane rotary air motor comprising: a cylinder including anopposed pair of spaced end walls; rotor mounted to rotate in saidcylinder between said end walls about an axis eccentric to the axis ofsaid cylinder and cooperating with said cylinder and end walls to form afluid chamber having separate high and low pressure portions that areangularly spaced from each other around said rotor;

at least one vane sliding in said rotor to project from thecircumference ofthe rotor and engage said cylinder for sealing betweensaid high and low pressure portions of said chamber;

means for applying fluid pressure beneath said vane uring it outwardlyagainst said cylinder while it is traveling through a portion of saidchamber located between said high and low pressure portions of saidchamber; and

said means including a pocket provided in each of said end walls inopposed relationship and separated from both said high and low pressureportions of said chamber, said pocket being closed except for itsopening in said each end wall and being effective to trap a volume ofthe pressure fluid in said chamber and to apply it to said vane to urgesaid vane outwardly as it travels between said high and low pressureportions of said chamber.

3. The motor of claim 2 wherein:

said pocket is located in the angular portion of said end wall relativeto the axis of the rotor that includes the lap portion of said chamber.

4. The motor of claim 2 wherein:

said pocket is located in the angular portion of said end wall relativeto the axis of the rotor where the vane is substantially fully extendedradially against said cylinder.

5. The motor of claim 2 wherein:

said pocket is located in the angular portion of said end wall relativeto the rotor between the inlet and exhaust ports of the motor.

1. A sliding vane fluid motor comprising: a cylinder including anopposed pair of spaced end walls; a rotor mounted to rotate in saidcylinder between said end walls about an axis eccentric to the axis ofsaid cylinder and having a series of vane slots extending longitudinallyand outwardly toward the cylinder; a vane sliding in each of said vaneslots for engaging the cylinder as the rotor rotates; a pair ofangularly spaced kidney ports in one of the cylinder end walls locatedin spaced angular relationship about the axis of the rotor andcommunicating with the ends of the vane slots as the rotor rotates tosupply fluid to and exhaust fluId from the vane slots; and at least oneclosed pocket provided in each of said end walls in opposed relationshipand angularly located about the rotor axis between and spaced from bothof said ports, said pocket being effective to trap a volume of fluidunder pressure for urging the vanes outwardly as the vane slots travelpast said pocket.
 2. A sliding vane rotary air motor comprising: acylinder including an opposed pair of spaced end walls; a rotor mountedto rotate in said cylinder between said end walls about an axiseccentric to the axis of said cylinder and cooperating with saidcylinder and end walls to form a fluid chamber having separate high andlow pressure portions that are angularly spaced from each other aroundsaid rotor; at least one vane sliding in said rotor to project from thecircumference of the rotor and engage said cylinder for sealing betweensaid high and low pressure portions of said chamber; means for applyingfluid pressure beneath said vane uring it outwardly against saidcylinder while it is traveling through a portion of said chamber locatedbetween said high and low pressure portions of said chamber; and saidmeans including a pocket provided in each of said end walls in opposedrelationship and separated from both said high and low pressure portionsof said chamber, said pocket being closed except for its opening in saideach end wall and being effective to trap a volume of the pressure fluidin said chamber and to apply it to said vane to urge said vane outwardlyas it travels between said high and low pressure portions of saidchamber.
 3. The motor of claim 2 wherein: said pocket is located in theangular portion of said end wall relative to the axis of the rotor thatincludes the lap portion of said chamber.
 4. The motor of claim 2wherein: said pocket is located in the angular portion of said end wallrelative to the axis of the rotor where the vane is substantially fullyextended radially against said cylinder.
 5. The motor of claim 2wherein: said pocket is located in the angular portion of said end wallrelative to the rotor between the inlet and exhaust ports of the motor.